I created a “vendor branch” of the MediaWiki stable releases for Mercurial users. (Git is, after all, pretty terrible by comparison.) Commit history goes from 1.21.2 back to 1.19.7.

You’ll do something like this to update:

$ cd your/personal/mediawiki/branch
$ hg pull -u
$ hg pull https://bitbucket.org/rianjs/mediawiki-vendor
$ hg merge tip
$ hg commit
$ hg push

Then deploy however you deploy. Check Special:Version to see that it’s updated.